The present invention relates to a compactly-designed and energy-saving pilot type controlled electromagnetic valve system for use mainly in controlling water supply.
In recent years, a so-called automatic meter check system utilizing a microprocessor-controlled water meter has been under development for the water supply systems in large cities. FIG. 3 shows the construction of a typical automatic meter check system. In FIG. 3, the meter check center A of the water supply side and the intensive meter check control unit B of the user side telecommunicate via a telephone line C to remotely and intensively control the reading of the water meter D of each user, as well as the opening and closing operations of the water supply controlled valve system E via the intensive meter check control unit B.
Such a water supply controlled valve system E usually takes the form of a pilot type controlled electromagnetic valve system as shown in FIG. 4. In FIG. 4, when the coil 1 of a solenoid is excited through remote control to attact a plunger 2 for separating a valve disk 3 from its valve seat 4, the water pressure inside the bonnet chamber 5 of the main valve F is released successively through a fluid path 6, a pilot valve chamber 7, and a fluid path 8 toward a secondary fluid path 9. Consequently, a diaphragm 11a is pressed upward by the primary fluid pressure P.sub.1 to push the valve disk 11 upward against the force of a spring 10. With the above operation, the primary fluid path 12 is communicated with the secondary fluid path 9 to consequently open the main valve F.
When the excitation of the coil 1 is interrupted, the pilot valve 3 moves downward to close the fluid path 8. With this operation, the fluid in the primary path is conducted into the bonnet chamber 5 of the main valve F successively through a primary pressure path 13, the pilot valve chamber 7, and the fluid path 6, by which the internal pressure of the bonnet chamber 5 is increased by the primary fluid pressure to press the valve disk 11 downward and consequently close the main valve F.
However, in a controlled electromagnetic valve system having the above construction, it is necessary to continuously supply a large current to excite the solenoid coil during the opening or closing operations of the main valve F. Therefore, a power source having a large capacity is necessary in order to cope with the large power consumption, which also incurs the problems of heat generation, etc.
Furthermore, for the integration of a driving power inside the controlled valve system, it is difficult to reduce the size of the valve, due the necessity of having a large-sized power source for the above reasons, which also results in a significant increase in the size of the water supply controlled valve system.
The present invention provides a novel controlled electromagnetic valve system for water supply permitting size reduction as well as power or energy savings, by eliminating the above-mentioned problems accompanying any conventionally controlled electromagnetic valve system for water supply, with the problems being: (1) the necessity of a large power capacity for the opening or closing operations of the valve system, leading to an increase in size of the driving power unit; (2) the difficulty in reducing the size of the valve system for structural reasons, etc.